So I balked at paying $70-100 for a Dell USB dongle that might not work and went ahead with the DIY cable. I cut up a USB extension and spliced the female end into a micro USB cable. Then I spliced the power feed from a regular USB cable into that. It's really hard to strip and solder wires that size. It took several attempts, but I can now display a dashboard while charging the tablet Just thought I'd loop back so the knowledge can be captured.